Concrete Curing Time Calculator

Work out concrete curing time instantly with clear inputs, formula shown and shareable results.

About Concrete Curing Time Calculator

Inverting the ACI maturity relation gives the age at which a target fraction of 28 day strength is reached: t = a x R / (1 - b R). Warmer concrete matures faster, so the reference time is scaled by the square root of the ratio of 20 °C to the actual curing temperature. Codes still require a minimum wet curing period regardless of strength gain.

Formulas

Age for target strength

t = a x R / (1 - b x R), R = target fraction of fc28

Temperature adjustment

t adjusted = t at 20 °C x sqrt(20 / T)

Worked example

With the default values below, Concrete Curing Time Calculator returns Curing days required of 6.18. Change any input above and every figure here is recalculated in your browser.

Inputs used

Target share of 28 day strengthaccepts 10–99 %: 70 %
Average curing temperatureminimum 2 °C: 25 °C
Cement typeone of Type I ordinary Portland, Type III rapid hardening: Type I ordinary Portland

Results

Curing days required: 6.18 days
Days at 20 °C reference: 6.91 days
Temperature factor: 0.894
Code minimum wet curing: 7 days

Step by step

1Values used
2Age for target strength
3Temperature adjustment
4Curing days required= 6.18 days
5Days at 20 °C reference= 6.91 days
6Temperature factor= 0.894
7Code minimum wet curing= 7 days

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Curing periods must follow the applicable concrete code and specification, not a strength estimate alone.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Curing periods must follow the applicable concrete code and specification, not a strength estimate alone.

Frequently Asked Questions

How is the Concrete Curing Time figure worked out?

t = a x R / (1 - b x R), R = target fraction of fc28. Inverting the ACI maturity relation gives the age at which a target fraction of 28 day strength is reached: t = a x R / (1 - b R).

Why is minimum wet curing separate from strength?

Curing protects against plastic and drying shrinkage cracking and develops the surface zone that resists carbonation and chloride ingress. Those benefits do not appear in a cube strength number.

What values do I need to enter?

This calculator takes 3 inputs: Target share of 28 day strength, Average curing temperature, Cement type. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.